Leucauramine derivate of benzoyl leuco methylene blue and transfer sheet coated therewith



Dec. 1, 1959 F, G, FR cls ETAL 2,915,415

LEUCA MINE IV BENZO L CO-METH NE B AND NS SHEET CO HEREWIT Filed June 5, 1958 l t L Wala.

LEUCAURAMINE DERIVATE F BENZOYLy LEUCO METHYLENE BLUE AND TRANS- 1 FER SHEET COATED THEREWITH Frederick George Francis, Old Southgate, London, and David John Neale, Woodford, England, assignors to Caribonum Limited, London, England, a British cont- Pally Application June 5, 1958, Serial No. 739,982

Claims priority, application Great Britain June 19, 1957 4 Claims. (Cl. 117-36) The present invention relates to improvements in colouring materials and is concerned, in particular, with colouring materials of the kind which can be readily produced by subjecting a colourless material to a chemical reaction.

A recent development which is an improvement over conventional carbon and other colour transfer sheet materials consists in the use of one or more colourless materials which, when transferred by the action of writing from ka colourless transfer sheet to a copy sheet having a suitable acid character, is or are readily converted into a coloured material in the form of a copy or record of the written matter. One notable advantage of this development is that colour is only produced by the actual process of writing and the transfer sheet material is substantially colourless.

One object of the present invention is to provide an improved colourless material of this kind, which can be carried in a coating on a colourless transfer sheet material and which, when transferred to an acid copy sheet or otherwise subjected to slightly acid oxidising conditions, is converted into a substantially light-fast coloured material.

The present invention consists in l0-(4-N-leucauraminebenzoyl)3,7-bis-(dimethy1amino)-phenothiazine, of the formula:

, s (GHmN more):

Ilm (onattNon-@Ntonm An alternative name for this compound is 4(3,7bis dimethylamino thiodiphenylaminoformyl) phenyl -leucauramine.

The present invention also consists in a transfer sheet material which carries a colourless coating which includes -(4Nleucaurarninebenzoyl)3,7bis(dimethyl amino)phenothiazine.

One general method of preparing leucauramine derivatives comprises the intercondensation of a primary amine 2,915,415 Patented (Dec. 1, 1959 ice ,Y

, 2 with Michlefs hydrol, 4,4'bis(dimethytamino) diphem ylcarbinol, by a reaction which can be `represented as:

where R can be any appropriate radical capable of forming a primary amine. The colourless compound of the invention can be made by condensing Michlers hydrol with 10-(4aminobenzoyl) 3,7 bis-(dimethylamino) phenothiazine, which is the para-amino derivative of benzoyl-leuco-methylene blue.

A further aspect of the present invention comprises a method of preparing the afore-mentioned colourless compound by the intercondensation of Michler`s hydrol with 10-(4-amino-benzoyl) 3,7 bis-(dimethylamino) phenothiazine, of the formula:

s www@ -Nwns), N

One notable advantage of the compound of the invention is that it is in effect an addition compound of leucauramine and beuzoyl-leuco-methylene blue and both of these substances, and many of their derivatives, are colourless materials which turn blue in the presence of a weak acid. Benzoyl-leuco-methylene blue and its amine derivative do not however develop colour immediately, but only after a time, and it is thought that this colour development is due to slow oxidation in the presence of weak acids. The compound of the invention can be considered to have a combination of the properties of these two substances and also has the further advantage that the blue derivative which it produces in the presence of an acid substance is substantially unaffected by light, so that copies of written matter produced by means of transfer sheet material according to the invention have excellent light-fastness and are substantially permanent. Moreover, the compound of this invention, namely, l0- (4-N-leucauramine-benzoyl)3,7bis (dimethyll amino)- phenothiazine, is substantially colourless in the commercially pure state, whether in solution or not.

In order that the invention may be readily understood, the following example is given.

To a hot solution of 4.6 grams of p-amino-benzoylleuco-methylene blue in 200 rnl. of 64 O.P. methylated spirit diluted with 13 ml. of water is added 3.2 grams E I 2,915,415 i l A u y .f

of Michlers'hydrol. After reducingl the pH to about' 6.0 with 5 N hydrochloric acid, the mixture is reuxed for two hours, cooled to about 2 C. and allowed to stand over-night at this temperature. The crystalline precipitate is filtered off, and washed with a little methylated spirit. The dried product may be recrystallised from Warm benzene, after addition of petroleum ether, to give pale yellow crystals melting at 249 C.

We claim:

2. A transfer sheet material, which carries a colourless coating which includes l0-(4-N-leucauramine-benzoyl) 3,7-bis-(Adimethybamino)-phenothiazine 3. A colourless composition Vof matter for use as transferable coatingapplied to transfer sheet material, which composition includes 10(4N-leucauraminebenzoyl)-3,7bis(dimethylamino)phenothiazine.

4. A method of preparing 10-(4N-leueauramnebenzoyl)-3,7-bis-(dimethylamino)phenothiazine,v which comprises intercondensing Michlers hydrol and p-aminobenzoyl-leucomethylene blue by adding Michlers hydrol to a water-containing methylated spirit solution of p-amino-benzoyl-leuco-methylene blue, reducing the pH to about 6.0 and reuxing the mixture.

References Cited in the lc of this patent UNITED STATES PATENTS Adams Mar.' vs, 1957 

2. A TRANSFER SHEET MATERIAL, WHICH CARRIES A COLOURLESS COATING WHICH INCLUDES 10-(4-N-LEUCAURAMINE-BENZOYL)3,7-BIS-(DIMETHYL-AMINO)-PHENOTHIAZINE. 